Sodium metabisulfite
General Product Information
| Article | Sodium metabisulfite |
| Synonyms | Sodium pyrosulfite, Sodium disulfite, Sodium metabisulphite, Sodium pyrosulphite |
| CAS No. | 7681-57-4 |
| EEG No. | 016-063-00-2 |
| EINECS No. | 231-673-0 |
| IMO | – |
| Tariff Code | 28321000 |
| UN No. | – |
| VLG/ADR | – |
Description
Sodium metabisulfite is an inorganic salt. It occurs as a white to pale yellow crystalline powder with a sharp, sulfurous odor. Highly soluble in water, it is widely used as a preservative, antioxidant and disinfectant. In contact with water or acids, it produces sulfur dioxide (SO2), which is responsible for its preservative action.
Characteristics
- Odor: Sulfurous.
- Hygroscopic: Yes.
- Color: White to light yellow.
- Grade: Technical.
- Solubility: Highly soluble in water.
- Shape: Crystalline powder.
Physical & Chemical Properties
| Chemical Structure | Na2S2O5 |
| Molar Weight | 190.10 g/mol |
| Melting Point | Approx. 150 °C (decomposes). |
| Boiling Point | – |
| Density | – |
| Refractive Index | – |
| pH | Approx., 4-5 (on 1% solution). |
Applications
Sodium metabisulfite is applied in various ways, for instance:
1. Chemical Industry
As a reducing agent or reagent at syntheses.
2. Cosmetic Industry
As a preservative and stabilizer in certain formulations.
3. Water Treatment
Used for dechlorination of water, effectively neutralizing chlorine.
4. Textile & Paper Industry
Applied as a bleaching and reducing agent.
5. Photography
As a fixer and antioxidant in development processes.
Interessing Links
- CAS Common Chemistry – Sodium pyrosulfite
- European Chemicals Agency (ECHA) – For chemical information and regulations.
- PubChem – Sodium Metabisulfite – Chemical information by the National Library of Medicine of the National Center for Biotechnology Information (NIH-NCBI).
- Wikipedia – Sodium metabisulfite